Firefox OS App Tutorial
Installing Firefox OS Simulator

First go to your firefox browser. Then go to options and then Add-ons. Then search for 'firefox os simulator'. If you found the simulator then install it.

After installation is done then go to the options and then click Developer then click to WebIDE from the dropdown list. Then you will be able to see a dashboard. If you have a done project then click 'project' in the menu bar, then click 'Open packeged app' from the dropdown list and then search and select your project file. If your file is uploaded successfully then you will be able to see your project files and folders on the sidebar of the dashboard. And if there is any problem in your project files the errors and warnings will be displayed on the screen.
If successfully uploaded then click on the 'Select runtime' option to run the firefox os simulator with a mobile phone view. Then return to the dashboard and press the play button ( |> ) to install the project file in the virtual phone. Then check if your app is running in the phone or not.